Electrical fuse



A WEST El' AL Jan. 8, 1935.

ELECTRICAL FUSE Filed Sept. 29, 1932 Patented Jan. `8, 1935 l y"s'mrss PATENT-ortica Application September `29, 1932, Serial No. 635,413

In Great Britain `October 2,1931 ,i r

This inventionrelatesnto electric fuses andrefers more particularly `to electric fuses tofZ the so called chemical` extinguisher type, that is electric; fusesA in which; `upon the.` fuse blowing, the

arc is extinguished by means o f some-name extinguishing liquid. This operation gives rise to an increaseof pressurein the vessel inwhich the y fuse is contained and to protect this vessel against such increase oftpressure it has been the-usual practice to-V provide a vent cap which-is intended to blow 01T at agiven pressure.

. It is'the object of the inventionto provide immovements `in such fuses and the invention comprisesthe arrangement that the increased pressure consequent upon the extinguishing of the arc-isgrelieved by the failure of a vent element l in the of the 4container at the side ofthe ,fusi-1l element. l

`This vent element ispreferably made of glass or like frangiblematerial and its failure consists inrffthe fracture thereof as distinct from its blowingaway `from its mounting. In this Way it is ensured that the failure-of the vent element will take place at a given suddenly applied pressure.

invention further `comprises-the` arrangethatvtherfuse element is .maintained in tension by means of` movable tension elements conniected `toit at b oth ends. l

rden that Vtheinvention may be the more clearly understood a `fvuseyin accordance there- 'with will no wA be describedreference beingmade to theaccompanyingdrawing which illustrates said fusein sectional elevation. l

Referring to this drawing the fuse element 1 is connected in circuit between two terminal contactferrules -2 `and 3 constituting the end caps of atubular container in the centre of which saidy fuse. is located. Said tiribularcontainery is constitutedA by vmeansiof two tubes -4 and 5of glass an"l intermediate centr-al tubular connecting element 6 ofmetalconnected to said tubes and overlapping the ends of said tubesfor a consider-- able space to protect them from the force of the explosion. Said connecting element 6 is formed with `a `laterally projectingboss 6a whose axis is at right angles to, and intersects, that of the container. 'I'he open end .of this ,boss 6a is closed by meanszofadisc of` glass orother frangible-material which is protected by means of a cover '8 havingan opening 8a through which said disc ,is exposed and-which disc isadapted to fracture when the fuse is blowrn `As yshownsaid disc `'7 has itsredge inwardly 4turned and secured within `a circular groove in a ring support-V9 and this ring supports/together with the'cover 8, is secured'by means V-ofqscrews 1'0, to a ring connecting element 11 secured,` sayxbyxscrewing, around the boss 6a, or alternatively cast in one integral piece with said boss 6a.

The fuse element 1 is held at its two ends by r portfor centering the clamp 12.

means of clamps 12 and 13 and these clamps are connected by means of screwconnecting elements 141; and .15' to the extremities of two tension coil springs'fl and '17 whose other ends are connected tothe Il'respective contact ferru1es:2 and 3. In this way said fuse element 1' is maintained in tension and the necessary electrical connections are also established.` In order torelieve the springs 16 and 17 of the majorfpart of the current, additional flexible-coppercables (notshown) may be providedconnecting the contact ferrules 2 and 3 with the appropriate screwconnecting elements 14 and`l5.

In order to enable powerful springs to beemployed thefuse itself consists ofhightensile Wire coated with silver. n

Thefuse element is surrounded by a tube 18 of arc resisting material whose extremities extend, as shown beyondthe ends of the` element 6 and which has a hole :in it whichregisters with the bore hole of the boss .6a. The diameter of this tube issuchthat lan annularspace remains between it and the container in which the arc extin'guishing liquid mayfreely flow. .This tube is supported bymeans of tworings ltli'ofstrip` metal which surround it andwhich are connected to a tubular element 20 of sheet metal secured, in the manner of a lining within the bore of the boss 6a, by means of screws21. Thesame `screws also secure a-secondtubular element 22 whose lower end is continued to form a lining for thehole in the tube 18and thereby constitute aguide con-V ning the impulse of the explosion and directing it straight on to the disc 7. This latter element has a projection 22a which formsV a loose sup- As shown the end portion of the contact ferru1e2 is separate from the skirt portion and` is connected theretov by means of screws 23. This is in order that the end-portion may be removed forlling, replenishing or replacing the varc extinguishing liquid. This necessitates that the springcl, instead of being connected, like the spring` 17, direct to the'end portion 'of the contact ferruleV is connected toa cross `bar or spider 24 mounted on the skirt portion.

What'we claim anddesire to vsecure'by Letters Patent is z" v 1. In` `an electric` fuse of the chemical extinguisher type, a separate vent member located `in the wall of'aiuse container and facing the side thereof, said ventrmemberbeingadapted to fail under the'iniiuence of pressure within said fuse container less than that required to fracture said container consequent upon the generation ofthe arc. l l l 2. In anelectriczfuseof theichemicallextinguisher type, a separate frangible vent member located in the wall of a fuse container, said separate vent member being adapted to fracture under the 'Jil influence of the increased pressure within said fuse container consequent upon the generation of the arc.

3. An electric fuse according to claim 2 wherein said separatevent member is of glass.

4. In an electric fuse of the chemical extinguisher type, a separate frangible vent member located in thefwall of a fuse container, and facing the side thereof, said separate vent member being adapted to fracture under the influence of the increased pressure within said fuse container consequent upon the generation of the arc.

5. In an electric fuse of the chemical extinguisher type, a fuse container constituted by two separate tubes, an intermediate connecting portion joining said tubes and closure members for the outer ends of said tubes, and a separate vent member located in the wall of said intermediate connecting portion, said Vent member being vadapted to fail under the influence of the in-" creased pressure within said'fuse container consequent upon the generation of the are.

6. An electric fuse according tofclaim wherein said two separate tubes are of glass and said intermediate portion is of metal. v f

7. In an electric fusebf the chemical extinguishertype, a fuse container constituted by two separate tubes of glass, an intermediate connecting portion joining said'tubes and overlapping kthe ends of said tubes' for a considerable space to protect them from the force of the explosion, closure members for the 'outer ends of said tubes, and a separate vent member located in the wall of said intermediate connecting portion, said vent member being adapted to fail under the influence of the increased pressure Within said fuse container consequent upon the generation of the are.

8. In an electric fuse of the chemical extinguisher type, a fuse container constituted by two separate tubes, an intermediate connecting portion joining said tubes having a laterally projecting boss, closure members for the outer ends of .said tubes, and a separate vent member closing the extremity of said boss, said vent member being adapted to fail under the influence ofthe increased pressure within said fuse container consequent upon the generation of the arc.

9. In an electric fuse of the chemical extinguisher type, a fuse container constituted by two separate tubes, anr intermediate connecting portion joining said tubes, closure members for the outer ends of said tubes, tension springs connecting the two ends of rthe fuse respectively to the two closure members, and a separate vent member located in the wall of said intermediate connecting portion and opposite said fuse, said vent member being adapted to fail under the influence of the increased pressure within said fuse container consequent upon the generation of the arc.

10.V Inan electric fuse of the chemical extinguisher type, a container having a fuse therein, the said container having a vent member in the side thereof communicable with the atmosphere, and a fracturable closurefor the vent adapted to fail under the influence of pressure within said fuse container consequent upon the generation of an arc less than that required to fracture the said container. f

11. In an electric fuse of the chemical extinguisher type, a fuse container, a separa-te vent member loca-ted in the wall oi the fuse container and facing the side thereof, said vent member being adapted to fail under the influence of the increased pressure within said fuse container consequent upon the generation of the arc, and a tube of arc resisting material surrounding the fuse and spacedfrom the wall of the container, said tube of arc resisting material having a hole in it opposite said vent member.

12.'In an electric fuse of the chemical extinguisher type, a fuse container constituted by two separate tubes, an intermediate connecting portion joining said tubes and having a laterally projecting boss, closure members for the outer ends of said tubes, and a separate vent member closing the extremity of said boss, said vent member being adapted to fail under the influence of the increased pressure within said fuse container consequent upon the generation of the arc, a tube of arc resisting material surrounding the fuse and spaced from the wall of the container, said tube of arc resisting material having a hole `in it opposite, said vent member, and a guide extending from said hole to said boss for confining the impulse of said increased pressure and directing it straight on to the vent member.

13. In an electric fuse of the chemical extinguisher type, a fuse container, a separate vent member located in the wall of the fuse container and facing the side thereof, and guiding means for confining the impulse of the increased pressure consequent upon the generation of the arc and directing it on to said vent member, said vent member being adapted to fail under the influence of said increased pressure. 4

14. In an electric fuse of thelchemical extinguisher type, a tubular container for the fuse element having a laterally projecting rboss opposite said fuse element, a separate vent member closing the extremity of said boss, a tube of arc resisting material surrounding the fuse element and spaced from the wall of the container, said tube of arc resisting material having a hole in it between said fuse element and said boss, and a guide extending from said 'hole to said boss for confining the increased pressure consequent upon the generation of the arc and directingit on to said vent member, said vent member being adapted to fail under the iniiuenceof said increased pressure.

15. In an electric fuse of the chemical extinguisher type, a fuse container constituted by two separate tubes, an intermediate connecting portion joining said tubes and closure members Vfor the outer ends of said tubes, and a separate frangible vent member located vin the wall of said' intermediate connecting portion, said vent member being adapted to fracture under the influence of the increased pressure within said fuse container consequent uponthe generation of the arc.

16..In an electric fuse of the chemical extinguisher type, a fuse container, a separate frangible `vent member located in the'wall of the fuse container and facing the side thereof, and guiding means for confining the impulse of the increasedpressure consequent upon the generation of the arc and directing it on to said vent member, said vent member being adapted to fracture under the influence of said increased pressure.

` ALLEN WEST.

VICTOR. BREEZE. 

